1. Field of the Invention
The present invention relates to a method of compensating luminance of an organic light-emitting diode (OLED), and more particularly, to a method of compensating luminance of an OLED operated with a transistor in a pixel cell and a display system thereof.
2. Description of the Prior Art
An organic light-emitting diode (OLED) is a light-emitting diode (LED) in which the emissive electroluminescent layer is a film of organic compound, where the organic compound can emit light in response to an electric current. OLEDs are widely used in displays of electronic devices such as television screens, computer monitors, portable systems such as mobile phones, handheld game consoles and personal digital assistants (PDAs). An active matrix OLED (AMOLED), which is driven by a thin-film transistor (TFT) which contains a storage capacitor that maintains the pixel states to enable large size and large resolution displays, becomes the mainstream of the OLED displays.
In a general OLED display, each pixel cell includes an OLED for displaying a gray scale in the pixel. The pixel cell receives a voltage signal from a timing controller. A TFT then converts the voltage signal into a driving current, which drives the OLED to emit light. The luminance of the OLED is determined by the driving current of the OLED. However, in the OLED display, the TFT indifferent pixels may possess an error or mismatch in the device parameter, which may result in different voltage-to-current conversion behaviors. In addition, there may also be a mismatch in the luminous efficiency of the OLED. After a long-time operation, the OLED display may undergo degradations in voltage-to-current conversion and luminous efficiency. Therefore, the uniformity of the OLED display may be influenced since different locations on the OLED display may possess different levels of degradations.
In order to improve the uniformity of the OLED display, an efficient compensation method for OLED and TFT parameters has become an important problem to be solved.